Phosphorus Dynamics: Relative Contributions by Bacteria and Zooplankton to Recycling Processes in Lakes Michigan, Huron and Erie

小行星9508087 北美五大湖生态系统磷的可利用性和供应率的差异是控制生产率、生物量发展和物种组成的主要因素。 尽管如此，磷酸盐的epilimnetic浓度均匀低，在所有的五大湖在夏季，和放射性示踪剂的研究表明，周转时间的环境池是几分钟到几十分钟，作为生物过程的结果。 在生产夏季的几个月里，现场浓度一般证明难以准确测量，但它似乎，在共同的海洋观测铵动力学，细菌占主导地位的通量在环境水平，而浮游植物占主导地位时，浓度略有增加。 在不同营养条件的五大湖中，示踪剂P的周转动力学和平衡分配之间存在差异，并且在单个五大湖内沿着近岸到离岸梯度存在差异。 在这项研究中要测试的主要假设是，微生物回收过程的相对幅度，和浮游动物的P回收，可预测的变化与整体初级生产，并与指数的P缺乏，使不同比例的回收P被纳入藻类与细菌在不同的湖泊。 这项研究工作将结合联合收割机明确的动力学模型P通量的实验，旨在量化的相对贡献的细菌，原生动物和后生动物的循环率在湖伊利，休伦湖和密歇根州。 一种新的分析方法，从海水中的淡水调查（镁诱导共沉淀的P），现在使易于调查的P动态和再生率的顶部稀释法。

9508087 Lehman Differences in availabilities and rates of supply of phosphorus to the ecosystems of the Great Lakes of North America are known to be major factors controlling rates of productivity, biomass development, and species composition. Nonetheless, epilimnetic concentrations of phosphate are uniformly low in all the Great Lakes during summer, and radiotracer studies demonstrate that turnover times of the ambient pools are minutes to tens of minutes, as the result of biological processes. In situ concentrations during the productive summer months have generally proven intractable to accurate measurement, but it appears that, in common with oceanic observations of ammonium dynamics, bacteria dominate fluxes at ambient levels, whereas phytoplankton dominate when concentrations are modestly increased. There are differences between turnover dynamics and equilibrium partitioning of tracer P in Great Lakes of differing trophic condition, and along inshore-to-offshore gradients within individual Great Lakes. The main hypothesis to be tested in this research is that the relative magnitudes of microbial recycling processes, and of P recycling by zooplankton, change predictably with overall primary production, and with an index of P deficiency, such that different proportions of recycled P are incorporated by algae versus bacteria in different lakes. This research effort will combine explicit kinetic models for P fluxes with experiments designed to quantify the relative contributions of bacterial, protozoan, and metazoan recycling rates in Lakes Erie, Huron and Michigan. A new analytical method adapted from sea water for fresh water investigations (magnesium inducted coprecipitation of P) now makes tractable the investigation of P dynamics and regeneration rates by is tope dilution methods.